As I write, the nation is waiting to see what the Supreme Court will say about gay marriage. The debates I've heard have centered mainly around whether or not gay people should be allowed to marry so that they can have the things that heterosexual couples take for granted.

The question is, do they actually want what heterosexual couples take for granted?

I just read an extraordinarily candid article by a gay man who promotes gay marriage. He's been in what he considers a committed relationship with another man for six years. They've had, he says, "varying understandings about monogamy at different times in [their] relationship." It is, he says, a well-known secret in the gay community that monogamy is by no means a given, even when a gay couple "marries" or otherwise swears allegiance to each other. He cites a recent long-term study of gay couples that shows that

This man applauds the canniness of the gay marriage movement for hiding this secret from mainstream, heterosexual America -- for putting on display gay couples who seem to live their lives like Ward and June Cleaver. Who cares that it happens to be Ward and Ward, or June and June? Love=love. He openly admits it: acceptance of gay marriage came about in part because straight people were fooled into thinking that gay marriage advocates are just as interested in monogamy and fidelity as the typical straight married couple.

He knows that most heterosexual married couples have tut-tutted away the procreative demands of sex. And now we are ready to admit that the unitive side is no big deal, either. One gay man he interviews says,

“I am discovering that straight couples dabble in the opening of their relationships, but they just don't talk about it. I believe it's the talking about it that bothers people, makes people uneasy, and gay people talk about everything,” he writes, adding, “We should talk about this no matter how uncomfortable we may feel initially.”

Do you see the argument? Heterosexual couples generally pledge fidelity to each other. Sometimes they are unfaithful anyway, but often, they recover and go on to have strong relationships. Since so many couples are unfaithful, more and more couples are willing to dispense with the idea that fidelity is even desirable. It's more and more common for couples to agree to be non-monogamous. And once something becomes common, we may call it normal.

To put his argument another way: all people say they want to be healthy, but then some people stab each other. Some people survive these stabbings, and regain full health. Others agree to be stabbed, or actively seek it. Therefore, stabbing is the new healthy. As long as you talk about it.

You need to know what's coming next, if it's not already here.

Nationwide gay marriage is probably a foregone conclusion. It's sort of like a law that you have to pass to find out what's in it: once gay marriage is commonplace, and is widely accepted as equal to heterosexual marriage, it will be safer for gay couples to stop pretending to be monogamous. And mark my words, this idea of culturally acceptable optional monogamy will stream quickly into heterosexual marriage, until the word "infidelity" will sound stodgy and obsolete to everyone's ears, gay or straight. "Infidelity" as a sin will rankle our sensibilities, and will sound about as dire as other unfashionable shalt-nots, like indocility, or a failure to be meek. It will become something that only prudes and witless sheep will fret about.

Today, infidelity still sounds like a bad thing to most people's ears. And that's a good thing. If gay marriage becomes commonplace, it's only a matter of time before we lose the very notion of infidelity. God help us. We've given up preserving our sense of virtue. If only we can cling to some sense of sin.